HIGH-FREQUENCY SOURCE OF EUF-RADIATION AND METHOD OF GENERATION OF RADIATION FROM LASER PLASMA Russian patent published in 2018 - IPC H05G2/00 G21K1/06 

FIELD: instrument engineering.

SUBSTANCE: invention provides a commercially available source of EUF radiation for ECF metrology and actinic inspection of lithographic UVF masks. It is realized by using a laser target in the form of a continuous stream of liquid lithium (1) circulating through the interaction zone in closed loop (9) by means of high-temperature pump (11). Collector mirror (7) is placed outside vacuum chamber (3) in a medium filled with an inert gas, and the output of EUF radiation beam (8) from interaction zone (2) to collector mirror (7) is carried out through EUV filter (12), which is the EUV output window of the vacuum chamber. Input window (5) for inserting laser beam (6) is provided with screening optical element (25). Evaporative purification of EUF filter (12) and shielding optical element (25) is provided by heating them to 350–450 °C. Protective cover (20) is installed around the jet of liquid lithium with a temperature above 180 °C.

EFFECT: technical effect: an increase in the reliability and lifetime of the source of the EUF radiation, simplifying its design and reducing the cost of operation while ensuring high brightness, high spatial and energy stability.

17 cl, 2 dwg